The research work described in this paper investigated the information literacy (IL) level of upper-secondary students in the southernmost provinces of Thailand and the problems that they encounter with respect to IL. Data were collected from a sample comprising of 390 students, who were selected by employing stratified random sampling. The research instruments included an IL test and a questionnaire concerning the problems encountered pertaining to IL. The data were analyzed based on percentages, means, and standard deviations. Moreover, significant differences were tested using t-tests, F-tests and a Scheffé test. The results revealed that, overall, the students' average level of IL, based on the seven standards, was at the Pass level. However, some students demonstrated Fail level of IL in Standard 3 (able to analyze, evaluate, and select the information required), as well as Standard 7 (have knowledge and the necessary skills to use ICT). Overall, the students encountered problems pertaining to IL at a moderate level. All variables, including sex, stream of study, GPA, and school location, affected the students' level of IL. However, only school location significantly impacted problems pertaining to IL. The researchers propose that teaching and learning activities should be redesigned utilizing collaborative teaching involving teachers, librarians, and ICT personnel in order to enhance students' IL. The Educational Supervisory Unit and the administrators of upper-secondary schools should set guidelines/ standards for providing modern ICT equipment to students, which they can use in classrooms, libraries, and computer rooms.